Fix seeking with WAV files.

Previously, rounding down to the nearest frame wasn't
being done correctly; seeking could seek into a sample.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122618668

library/src/main/java/com/google/android/exoplayer/ExoPlayer.java

@@ -31,7 +31,7 @@ import android.os.Looper;
  * <a name="Assumptions"></a>
  * <a name="Assumptions"></a>
  * <h3>Assumptions and player construction</h3>
  * <h3>Assumptions and player construction</h3>
  *
  *
- * <p>The implementation is designed make no assumptions about (and hence impose no restrictions
+ * <p>The implementation is designed to make no assumptions about (and hence impose no restrictions
  * on) the type of the media being played, how and where it is stored, or how it is rendered.
  * on) the type of the media being played, how and where it is stored, or how it is rendered.
  * Rather than implementing the loading and rendering of media directly, {@link ExoPlayer} instead
  * Rather than implementing the loading and rendering of media directly, {@link ExoPlayer} instead
  * delegates this work to one or more {@link TrackRenderer}s, which are injected when the player
  * delegates this work to one or more {@link TrackRenderer}s, which are injected when the player

library/src/main/java/com/google/android/exoplayer/extractor/wav/WavHeader.java

@@ -30,7 +30,7 @@ import com.google.android.exoplayer.C;
   private final int blockAlignment;
   private final int blockAlignment;
   /** Bits per sample for the audio data. */
   /** Bits per sample for the audio data. */
   private final int bitsPerSample;
   private final int bitsPerSample;
-  /** The pcm encoding */
+  /** The PCM encoding */
   private final int encoding;
   private final int encoding;
 
 
   /** Offset to the start of sample data. */
   /** Offset to the start of sample data. */
@@ -50,22 +50,8 @@ import com.google.android.exoplayer.C;
 
 
   /** Returns the duration in microseconds of this WAV. */
   /** Returns the duration in microseconds of this WAV. */
   public long getDurationUs() {
   public long getDurationUs() {
-    return (getNumFrames() * C.MICROS_PER_SECOND) / sampleRateHz;
-  }
-
-  /** Returns the number of samples in this WAV. */
-  public long getNumSamples() {
-    return dataSize / getBytesPerSample();
-  }
-
-  /** Returns the number of frames in this WAV. */
-  public long getNumFrames() {
-    return getNumSamples() / getNumChannels();
-  }
-
-  /** Returns the bytes per sample of this WAV. */
-  public int getBytesPerSample() {
-    return blockAlignment / numChannels;
+    long numFrames = dataSize / blockAlignment;
+    return (numFrames * C.MICROS_PER_SECOND) / sampleRateHz;
   }
   }
 
 
   /** Returns the bytes per frame of this WAV. */
   /** Returns the bytes per frame of this WAV. */
@@ -92,7 +78,7 @@ import com.google.android.exoplayer.C;
   public long getPosition(long timeUs) {
   public long getPosition(long timeUs) {
     long unroundedPosition = (timeUs * averageBytesPerSecond) / C.MICROS_PER_SECOND;
     long unroundedPosition = (timeUs * averageBytesPerSecond) / C.MICROS_PER_SECOND;
     // Round down to nearest frame.
     // Round down to nearest frame.
-    return (unroundedPosition / numChannels) * numChannels + dataStartPosition;
+    return (unroundedPosition / blockAlignment) * blockAlignment + dataStartPosition;
   }
   }
 
 
   /** Returns the time in microseconds for the given position in bytes in this WAV. */
   /** Returns the time in microseconds for the given position in bytes in this WAV. */